Abstract
We study the evaporation process by means of a single evaporation source putting in the mixture of two hole-transport materials(HTMs) for organic light-emitting diodes. In the case of the mixture of two HTMs with large difference, 120, of evaporation threshold temperature (Te), when evaporation temperature rises at a constant rate with time, the HTM with higher Te vaporizes after the HTM with lower Te vaporized. In the case of the mixture of TPD:α-NPD =1:1 with the difference of 50K, only a single evaporation curve is observed in the temperature region between the evaporation curve of only TPD and that of only α-NPD. The fabricated thin films using the mixture of TPD:α-NPD =1:1 under a constant temperature consist of TPD:α-NPD = 10:1. This is because the Te of TPD increases and that of α-NPD decreases.
